Keel bone fractures affect the majority of laying hens in cage-free and aviary systems, causing chronic pain that is a major unresolved welfare challenge.
Keel bone fractures represent a major welfare problem in the cage-free systems that were adopted to improve welfare compared to battery cages. The fractures are caused by collisions during flight and landing in multi-tier aviary systems, and their prevalence is high across system designs. Research is active on both preventive interventions — perch design, landing zone materials, light management during flight activity — and genetic solutions. The welfare challenge is urgent given the scale of cage-free transition globally and the evidence that this large fraction of hens is experiencing chronic pain.